*{
    box-sizing: border-box;
}
body{
    margin: 0;
    font-family: Arial, Helvetica,'Microsoft Yahei',sans-serif;
}

/* 公共类 */
.flex{
    display: flex;
    justify-content: space-between;
    align-items: center;
}
.padded{
    padding: 1rem;
}